1. Field of the Invention
The present invention relates to a fuel injection control device for an internal combustion engine and more particularly to a fuel injection control device for an internal combustion engine which ensures a stable carburetion condition at the start of the engine.
2. Description of Background Art
A fuel injection control device in an internal combustion engine performs a sequential injection in which fuel is injected in time with each intake stroke in each cylinder, in its normal operation. However, at the start of the internal combustion engine it is impossible to perform a sequential injection after the start of cranking until completion of the stroke identification because intake stroke timing is unknown. Therefore, it has been known that instead of a sequential injection, simultaneous injection is performed to supply fuel where fuel is injected into all cylinders at a time.
JP-A No. 280654/1989 discloses an electronically controlled fuel injector for an internal combustion engine in which after a start switch is turned on and cranking is started with a simultaneous injection being performed upon each crank rotation while the start switch is on. Thereafter, the start switch is turned off and a stroke identification is completed with a group injection being once performed where fuel is injected into each of several groups of cylinders, before proceeding to a sequential injection. This device can reduce the possibility of under-fueling or over-fueling for particular cylinders as compared with the approach that simultaneous injection is switched to sequential injection immediately after the start switch is turned off.
However, even with the technique disclosed in JP-A No. 280654/1989, injection timing in relation to the compression top dead center differs among cylinders in the simultaneous injection period before completion of the stroke identification. For this reason, a problem exists in that the condition of fuel carburetion differs among cylinders until completion of the stroke identification.